1. Field of Invention
The invention relates to a module for controlling and expanding serial transmission, especially a controlling and expanding module for serial data transmission between a chip and a plurality of interface units.
2. Related Art
Individual chips (such as CPUs) use interfacing integrated circuits (interfacing ICs) on serial interfaces and other devices to execute serial transmission. There are many types of serial interfaces, such as RS232, RS 485, etc; therefore, a chip usually needs to be connected to many interfacing ICs for practical purposes.
However, when a chip needs to be connected to more than two interfacing ICs, it needs more than two serial transmission ports, or a special expansion module to enable serial transmission. The current expansion modules are not only structurally complex, and also expensive to fabricate, and so raise the overall cost of the complete product.
Thus, it is very important to develop a simple and low cost controlling and expanding module for serial transmission.